Effect of Azotobacter chroococcum on nutrient uptake in Amrapali mango under high density planting.
Ahmad M. F., Saxena S. K., Sharma R. R., Singh S. K.
Author Affiliation: Division of Fruits and Horticultural Technology, IARI, New Delhi 110 012, India.
Indian Journal of Horticulture 61 : 348-349
Abstract : Experiments were conducted during 1996 and 1997, in New Delhi, India, to evaluate the effects of different doses of N fertilizer (1/3, 2/3 and full dose of N, i.e. 145 g urea/tree), with or without biofertilizer (Azotobacter chroococcum strains M-4 and CB-15), on the nutrient uptake of 10-year-old Amrapali mango grafted on Kurukkan rootstock at a distance of 3×3 m (1600 plants/ha). The treatments were: (T0) control; (T1) full dose of N + M-4; (T2) full dose of N + CBD-15; (T3) 2/3 dose of N + M-4; (T4) 2/3 dose of N + CBD-15; (T5) 1/3 dose of N + M-4; (T6) 1/3 dose of N + CBD-15; (T7) M-4 only and (T8) CBD-15 only. All plots received a single dose of P2O5 (335 g/tree) and K2O (420 g/tree) in the form of single superphosphate and muriate of potash, respectively. Leaf N content in all treatments increased after the fruit harvest in July with the application of higher doses of urea, whether applied singly or in combination with A. chroococcum. T2 showed the highest uptake of N at flowering and after harvest, followed by treatments 7 and 8 (both with A. chroococcum only). It clearly indicates that the A. chroococcum as a biofertilizer compensates for the absence of N fertilizer in mango. All treatments increased leaf P content over the control, with the highest being observed in T1, T2 and T6. A. chroococcum application favoured P uptake. Leaf K content was generally higher after harvest than at flowering, with the highest values being observed in T4 and T2. Leaf P content was relative higher with the application of CBD-15 compared with M-4. Micronutrients (e.g. Cu and Zn) increased at flowering and after harvest irrespective of the treatments, but T1 and T4 showed comparatively higher values, indicating that both strains of A. chroococcum have equally effective for the uptake of both micronutrients.